ansible/sshd: allow configuring insecure ssh access to the container

This is intended to only be used during testing, when VALVE_INFRA_SSH_INSECURE=true it configures the sshd to allow the root account to connect without a password or key. This is required for running the container in CI, e.g. the integration testing, where the valve-infra-container container image already exists, and will not have any authorized_key installed in it vivian to use.

For good measure, I also added a profile.d script to print a big fat warning when "insecure ssh" mode is enabled.

This defaults to not modifying the sshd config if the var is unset/false, so container security is not compromised.